Bloodworm

From The Aquarium Wiki

Blood worm (Chironomidae [Ky-ro-nomi-day] tetans) is the larvae of the midge fly. It is a small (3 cm [1.2"]), long, thin, bright red larvae which grows in stagnant pools.

The blood worm has red iron-porphyrin protein in its blood and tissue which gives it its characteristic colour. This larva is very important in the wild aquatic food chain. Therefore, it is one of the primary live foods fed to virtually all aquarium kept freshwater aquatic animals.

Special notes

There have been medical reports that people can develop an allergy to this creature over time (takes 1 – 2 years) just by touching it, breathing in dried blood worm dust or its contaminated water. A bad reaction (itchy or swollen eyes, coughing, shortness of breath, skin swells) to this fish food can build up over several years and you should be aware of this.[1]

As with giving your animals any live food, there is the risk of adding parasites and diseases to your tank. Frozen, jellied and dried bloodworm is usually irradiated to remove these dangers. But check the packaging.

Watch out for sales gimmicks

With some low quality frozen bloodworm the suppliers will add in their ingredient list extra vitamins so the food looks more nutritious. This can be a sales gimmick rather than any benefit to your fish. These vitamins are usually added in the water they are frozen with and these will break down in minutes when exposed to the aquarium. You can often tell if your supplier does this by examining the ingredients list. If the list has the vitamins in brackets i.e. 'Blood worms (vitamin B12, C)' then these are inside the worm. If the items are listed after the blood worm with a comma then they're in the water.